Cobalt has been demonstrated to be an essential mineral element for beef
cattle, apparently exerting its principle effect in the ruminant animal
through the formation of vitamin B12 in the rumen. Deficiencies of this
element have been experienced by many cattlemen in South Florida. Although
it is an essential mineral element a very small amount is required to pre-
vent a deficiency, with good results obtained by the inclusion of one ounce
of cobalt sulfate in each 100 pounds of complete mineral mix.

Recent articles have reported that cobalt, administered orally, in the
form of a "pellet"of high specific gravity, will stay in the rumen or reti-
culem of the ruminent animal for a prolonged period of time and result in
any increased rate of growth, even though a complete mineral mixture may be
provided. The cobalt pellet has been called a "bullet". The widespread
interest in this approach to cobalt administration resulted in the initiation
of three field experiments with this product. The purpose of this report is
to present the results of these three studies.

Experiment 133-a

This experiment was established at the Collier Cattle Company, Imokalee,
Florida, July 28, 1959. Ninety-one, mature Hereford cows, some indicating
considerable age, were divided into two groups, with one group receiving the
cobalt bullet. The treated animals were each given, orally, one cobalt
bullet. This bullet contains 90 percent cobalt oxide.

After treatment all animals were kept in one group and received common
management. The cattle in the experiment were handled as usual, with no
special treatment other than the cobalt bullet. The results of this study
are presented in table one.

2/ Acknowledgment is made to the Collier Cattle Company, Imokalee, Florida
and the Hayes Ranch, Clewiston, Florida for excellent cooperation which
made these studies possible. The assistance of T. Swager and Joe
Crockett in the identification of these animals is appreciated.

The cattle in this experiment were run under range conditions and at
the conclusion of the experiment it was possible to weigh only 61 of the
original 91 head. Based on the average initial and final weight of these
61 animals, the animals not receiving the bullet had an average weight
loss of 72 pounds, as compared to 35 for the treated animals. It was not
possible to determine the effect of treatment on the progeny of the cows.
Neither was it possible to determine if the weight advantage continued during
the following spring and summer period.

Experiment 133-b

The purpose of this experiment was to evaluate the cobalt pellet in
the Belle Glade area. It was conducted at the Everglades Experiment Sta-
tion, with the cobalt treatment being administered in addition to all other
management practices.

Seventy-six yearling steers, of predominately Brahman x Angus breeding,
were divided into two equal groups. All animals were treated twice for liver
flukes and intestinal and stomach worms prior to being placed on e:q-:e'iment.
The animals were allotted to treatment at random, within weight groups, with
each of the treated animals receiving one cobalt bullet, identical to the
ones used in Experiment 133-a. These animals were fed through the winter
on a roughage study, after which they were placed in a feeding experiment.
Each animal received an average of 0.1 of a pound of a complete mineral
mixture daily, when on the roughage test and when being fed. If the animals
were not fed they were provided the same mineral free choice. This mineral
contained 0.03 percent of cobalt. The results of this experiment are pre-
sented in table two.

Table 2. Summary of average weight changes of steers at Everglades Station,
from 11-23-59 to 8-17-60.

There was no weight gain advantage obtained by the administration of
the cobalt bullet to the yearling steers at the Experiment Station.

Experiment 133-c

The purpose of this study was to determine the value of the cobalt pellet
for yearling steers in the Clewiston area. It was conducted at the Hayes I., -h,
from February 3, 1960 to September 7, 1960.

One hundred and fifty three grade Brahman yearling steers were used. The
experimental animals had been treated twice for liver flukes at the time of
weaning. At the initiation of the experiment each animal received 3 ounces
of a phenothiazine drench made of 7 pounds of active ingredient per 3 gallons
of water. This treatment was repeated three weeks later. As in the other
two studies, the experimental treatment was used in addition to the normal
management practices followed at the ranch. At the beginning of the study
the steers were grazing Fangolagrass, on a mucky-sand soil. They were re-
ceiving mineral-fortified blackstrap molasses, free choice, plus 300 pounds
of a 41 percent pellet per day for the 153 steers. The treated animals were
each given one cobalt bullet. The experimental results are presented in
table three.

Table 3. Summary of average weight changes of yearling steers at Hayes
Ranch, from 2-3-60 to 9-7-60.